Among the input/output interfaces of information processing apparatus such as personal computers (PCs), the serial port, parallel port, ISA (industry standard architecture) bus, and IDE (integrated drive electronics) are widely used. Conventional information processing apparatus employ, in addition to the above interfaces, the USB (universal serial bus), IEEE 1394, PCI (peripheral component interconnect), extended IDE, ATA (AT attachment) etc.
In spite of the above advancements of the computer input/output standards, there may occur a case that the OS (operating system) needs to access a general-purpose interface. Such general-purpose interfaces are interfaces that can be used safely in many environments. One of such general-purpose interfaces is the UART (universal asynchronous receiver transmitter). The UART sends and receives data via a serial transmission line. Furthermore, the UART converts a parallel signal transmitted from a PC into a serial signal and converts a serial signal transmitted from a peripheral device into a parallel signal.
It can be said from the above described perspective that the best method for accessing the kernel (OS) is to use a device that is connected to a UART. In these circumstances, an emulation-related technique has been proposed in which a UART is virtualized and a non-UART device connected to the resulting virtual UART is used for the purpose of debugging the OS. An example of such technique is described in JP-A-2006-309764.
However, where this conventional emulation technique is applied, the non-UART device is recognized by the OS and put under the control of the OS. Therefore, there is a probability that the non-UART device is excluded from the control of firmware such as the BIOS (basic input/output system) to disable the debugging.